docs: def _check_servers(self):
          """Check the servers variable and convert in a valid tuple form"""
          new_servers = []
  
          def check_format(server):
              if server.scheme not in ["thrift", "http", "https"]:
                  raise RuntimeError("Unable to recognize protocol: \"%s\"" % _type)
  
              if server.scheme == "thrift":
                  if not thrift_connect:
                      raise RuntimeError("If you want to use thrift, please install thrift. \"pip install thrift\"")
                  if server.port is None:
                      raise RuntimeError("If you want to use thrift, please provide a port number")
  
              new_servers.append(server)
  
          for server in self.servers:
              if isinstance(server, (tuple, list)):
                  if len(list(server)) != 3:
                      raise RuntimeError("Invalid server definition: \"%s\"" % repr(server))
                  _type, host, port = server
                  server = urlparse('%s://%s:%s' % (_type, host, port))
                  check_format(server)
              elif isinstance(server, six.string_types):
                  if server.startswith(("thrift:", "http:", "https:")):
                      server = urlparse(server)
                      check_format(server)
                      continue
                  else:
                      tokens = [t for t in server.split(":") if t.strip()]
                      if len(tokens) == 2:
                          host = tokens[0]
                          try:
                              port = int(tokens[1])
                          except ValueError:
                              raise RuntimeError("Invalid port: \"%s\"" % tokens[1])
  
                          if 9200 <= port <= 9299:
                              _type = "http"
                          elif 9500 <= port <= 9599:
                              _type = "thrift"
                          else:
                              raise RuntimeError("Unable to recognize port-type: \"%s\"" % port)
  
                          server = urlparse('%s://%s:%s' % (_type, host, port))
                          check_format(server)
  
          self.servers = new_servers